Cancer, the Crab is best viewed during the month of March.
Click on image for full size
Windows to the Universe original image


Cancer, the Crab, is a member of the Zodiac, a group of constellations that the Sun travels through each year. Cancer spends half of the year in the sky. It first rises in December and is visible through June. Although the Crab is one of the more famous constellations, it is mostly made of dim stars.

Fortunately, Cancer is surrounded by much brighter figures, like Gemini and Leo. If you use your imagination, a figure that looks like a crab appears. Looking at the picture, one can see a body with two "claws" coming out of it. The head of the crab contains two stars named Asellus Borealis and Asellus Australis, whose names mean Northern and Southern Ass. These stars were believed to be the two asses that Dionysus and Silenus rode on during the battle against the Titans. The loud noises of the animals scared the Titans, and so the gods won the battle that day.

The constellation itself came from Greek myth. In the story of Heracles and the Twelve Labors, the warrior had a great battle with the monster Hydra. Hera sent a giant crab to hinder Heracles. However, its grasp did little to stop the hero, who simply crushed the crab beneath his foot. Hera put the crab in the sky to honor its bravery.

Right next to the head is a star cluster known as Praesepe, or the Beehive. To the naked eye, it looks like a fuzzy cloud. Some civilizations believed it was an opening for souls to come down from Heaven. Galileo later discovered that it was really a cluster of stars. It was later named the Beehive because astronomers think the cluster looks like a swarm of bees.

There is a dim galaxy located in the southeast corner of the constellation called NGC 2275.

You might also be interested in:


Many cultures have seen distinctive patterns, called constellations, formed by the stars in the heavens. Constellations are usually comprised of bright stars which appear close to each other on the sky,...more

Globular Clusters

If you think that this globular cluster looks like a very round elliptical galaxy, you would be right! Elliptical galaxies and globular clusters have a lot in common. There is no gas or dust in a globular...more

Northern Hemisphere Constellations

Many different constellations fill the evening sky in the northern hemisphere. Depending on your location and the season, different constellations can be seen. Northern circumpolar constellations can be...more

Southern Hemisphere Constellations

Many different constellations fill the evening sky in the southern hemisphere. Depending on your location and the season, different constellations can be seen. Southern circumpolar constellations can be...more


The constellation Carina is known as the Keel, which is the bottom part of old ships. Carina was originally a part of Argo Navis, which was a huge boat in the night sky. It has since been divided into...more

It All Depends On Your Point Of View

In most cases, however, the stars that we see that seem to be "close" to each other actually are quite far apart, some stars are much closer or farther than others as is shown in the example below of Ursa...more

As the World Turns

In our time, scientists (and most people!) know that the constellations seem to move across the sky because the earth rotates on its axis. What, you may ask, does the turning of the earth have to do with...more

The Changing Night Sky

If you look at the night sky at different times of the year you see different constellations. This change is due to the motion of the Earth in its orbit around the Sun. As the Earth revolves about the...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA